Process for hydrodesulfurizing hydrocarbons



as hma PROCESS FOR HYDRGDESULFURIZING I HYDRUCARBGNS Grant W. Hendricks,Bren, Caiifl, assignor to Union Oil Company of California, Los Angeles,Calif., a corporation of (Ialifornia No Drawing. Application March 15,1954, Serial No. 416,417

8 Claims. (Cl. 196-28) This invention relates generally to catalysts andto catalytic processes for the conversion of hydrocarbons andhydrocarbon mixtures. More particularly, this invention relates to a newand improved method for a preparation of catalysts comprising cobalt andmolybdenum oxides supported on carriers and to methods for using suchcatalysts.

Supported catalysts containing cobalt and molybdenum have been preparedand described in U. S. Patent 2,393,288 issued to A. C. Byrns. Thecatalysts described therein were prepared by coprecipitating cobalt andmolybdenum oxides in molecular combination as cobalt molybdate alongwith, or in the presence of, a suitable carrier such as alumina. Asupported co-impregnate'd cobalt molybdate catalyst has been describedin copending application 559,650 filed October 20, 1944 by P. G. Nahinet al., now U. S. Patent 2,486,361.

It has now been found that an improved cobalt-molyb denum catalystsupported on a suitable carrier can be prepared by a two-stageimpregnation process described herein and that catalysts prepared bythis new method are easier to prepare, possess superior activity andhave other desirable features and properties.

It is an object of this invention to simplify the preparation ofsupported cobalt-molybdenum-containing catalysts and to improve thecatalytic activity of such catalysts.

it is a further object of this invention to provide a method for thepreparation of supported cobalt-molybdenum-containing catalysts whichmethod affords greater control of the final catalytic composition duringthe preparation and manufacture.

it is another object of this invention to provide a new suuportedcatalyst and to provide method for the use thereof for hydrocarbonconversion processes such as desulfurization, denitrogenation,hydrogenation, hydroforming and the like.

Briefly this invention relates to the preparation of a supportedcobalt-molybdenum oxide catalyst which is prepared by the impregnationof the carrier in two separate and distinct steps. A suitable adsorbentcarrier, e. g. activated alumina, alumina-silica, titania or the like isfirst immersed in an aqueous solution of a soluble molybdenum-containingsalt, such as for example, an ammoniacal ammonium molybdate solution.The impregnated carrier is drained of the excess solution, is dried andheated to a temperature sufiicient to decompose or oxidize themolybdenum-containing salt to form molybdic oxide. The carriersupporting the molybdic oxide is thereafter immersed in an aqueoussolution of a soluble cobalt-containing salt such as for example aqueouscobaltous nitrate. The reimpregnated carrier is drained of the excesssolution, dried, and heated to a temperature sufficient to decompose oroxidize the cobalt-containing salt to form cobalt oxide. The resultingcatalyst may be employed for various hydrocarbon conversions describedhereinafter such as desulfurization, denitrogenation, hydrogenation,hydroforming and the like.

nited States Patent.

2,728,?10 Patented Dec. 27, 1955 The carriers which are suitable and maybe employed for distending the mixture of cobalt and molybdic oxidesaccording to the process in this invention comprise alumina, silica,zirconia, thoria, magnesia, magnesium hydroxide, titania or anycombination of these. The preferred carrier is activated, gel-typealumina and particularly alumina gel containing about 3 to 8% of silica.The presence of the small amount of silica in the alumina serves tostabilize the resulting catalyst andprolongs the catalyst life as isdescribed in U. S. Patent 2,437,532 to H. C. Huffman.

The carrier is normally shaped into the physical form desired for thecatalyst prior to the impregnation steps. For this purpose the driedcarrier is usually ground, mixed with a lubricant such as graphite orhydrogenated vegetable oil, and pilled. In the activation of the carrierthe lubricant is removed by combustion. Alternatively the carrier may beused in granular form or ground into powder and extruded. Where thecatalyst is to be employed in a fluidized process, such as in fluidizeddesulfurization, denitrogenation, and the like, the carrier is formedinto a finely-divided state or is ground into a fine state and isthereafter impregnated. In the case of fluidized processes the carriercan be impregnated in larger form, e. g. granules, pills, etc., andthereafter ground to the desired powder size for the processing.

The molybdenum-containing impregnation solution is preferably ammouiacalammonium molybdate although aqueous solutions of other solublemolybdenum compounds may be employed. In the preferred method, ammoniumparamolybdate is dissolved in about 14% aqueous ammonia and theresulting mixture is diluted with distilled water or with more dilutedaqueous ammonia to form a clear ammonium molybdate solution of thedesired concentration. The concentration of the ammonium molybdatesolution will depend on the particular carrier being employed and on thedesired concentration of molybdenum in the finished catalyst. Wherealumina or alumina-silica carriers are employed, and a finished catalystcomprising between about 6 to 16% of M00; is desired, themolybdenum-containing impregnation solutions will have a concentrationof molybdenum ranging from about 12 to 32 g. of MoOs/ ml.

The cobalt-containing impregnation solution is preferably an aqueoussolution of cobaltous nitrate although other water-soluble compounds ofcobalt may be employed. Thus cobalt chloride and cobalt sulfate may beemployed in the impregnation solutions although these compounds are moredifiicultly decomposable to active forms and require both heat andoxidation to complete their conversion to the oxide. The concentrationof the cobalt-containing impregnation solution will depend upon thecarrier being employed and the desired concentration of cobalt in thefinished catalyst. Where alumina or alumina-silica carriers are employedand where a final catalyst composition containing from about 2 to- 10%by weight of C00 is desired, the concentration of the cobaltimpregnation solution will range from about 4 to 23 g. of (300/ 100 ml.

In. the preparation of the catalyst the carrier is first activated byheating in order to render it sufiiciently adsorbent to be impregnated.Such activation may for example be effected by heating for 2 to 6 hoursat 400 to 600 C., The carrier is then cooled and. immersed in themolybdenum-containing impregnation solution of the type describedhereinbefore. The impregnation solution is absorbed by the carrier andthe excess impregna tion solution is-thereafter removed. The impregnatedcarrier isdrained and dried in a low temperature oven toremove the bulkof the water. Following the drying at, for example, 90 to 110 C. themixture is activated by heating it to a temperature of, for example, 400to 600 C. for two to six hours in order to decompose the molybdenum saltto M003.

The carrier supporting the molybdic oxide is then cooled and immersed inthe cobalvcontaining impregnation solution of the type describedhereinbefore, to absorb the cobalt-containing solution. The excesssolution is again removed and the impregnated material is drained anddried at low temperature for example 90 to 110 C. The material is againactivated by heating at 400 to 600 C. for two to six hours in order todecompose the cobalt-containing compound to cobalt oxide. The finishedcatalyst prepared by this method is usually reduced in the presence ofhydrogen at a temperature between 700 and 1100 F. prior to its use.

The finished catalyst is useful for effecting various hydrocarbonconversion reactions such as desulfurization, denitrogenation,hydrogenation, hydroforming, reforming, cracking, destructivehydrogenation and the like.

During usage varying amounts of deposits comprising mostly carbon,nitrogen and sulfur compounds accumulate on the catalyst and areperiodically removed by regeneration. Regeneration is effected bypassing air diluted with flue gas, steam, nitrogen or other inert gasover the catalyst to combust the deposits while maintaining thetemperature of the catalyst between 800 and 1050 F. The combustion iscompleted in the presence of undiluted air while maintaining thetemperature of the catalyst between 800 and 1050 F. The regeneratedcatalyst after reduction with hydrogen has practically the samecatalytic activity as the freshly prepared catalyst even after a largenumber of regenerations.

For the purpose of desulfurizing petroleum stocks, shale distillates andthe like, the catalyst of this invention is employed under the followingconditions: reaction temperatures between about 600 to 1000 F.,pressures be tween about atmospheric to 5000 lbs. per sq. in. or moreand at space velocities between about 0.2 and 10.0 volumes of liquidfeed stock per volume of catalyst per hour,.and 500 to 10,000 cu. ft. ofadded hydrogen per barrel of feed. The particular set of conditions isdetermined by the stock to be desulfurized and by the nature of theproduct desired. v

The catalyst in this invention can also be employed for denitrogenationof such stocks as coal tar distillates, shale oils and heavy petroleumdistillates whereby up to 99% of the nitrogen and substantially 100% ofthe sulfur can be removed simultaneously. For denitrogenation of suchstocks the following conditions are employed:

reaction temperatures between about 700 and 1000 F., pressures betweenabout 500 and 10,000 lbs. per sq. in., feed rates between about 0.2 and10.0 volumes of liquid feed stock per volume of catalyst per hour, andabout 1,000 to 10,000 cu. ft. of added hydrogen per barrel of feed. Forthe removal of nitrogen it is generally desirable to employ a two-stagedenitrogenation process wherein the ammonia synthesized in the firststage is removed from the first-stage product prior to its entry intothe second stage denitrogenation and wherein the ammonia and hydrogensulfide are removed from the recycle hydrogen gas streams in each stage.Under these conditions the maximum efficiency forremoving nitrogen fromthe stocks is obtained.

The catalyst of this invention may also be employed for the processgenerally termed hydroforming, which process serves to reform a gasolinerange hydrocarbon stock and increase its aromatic content. Forprocessing stocks for the purpose of reforming and increasing theiraromaticity, the following conditions are employed: reactiontemperatures between about 800 to 1200 F., pressures between about 50 to1000 lbs. per sq. in., space velocities between about 0.2 and 4.0volumes of liquid feed stock per volume of catalyst per hour, and about1,000 to 10,000 cu. ft. of added hydrogen per barrel 4 of feed. Thespecific conditions are determined by the nature of the specific feedstock employed and the quality of the product desired.

Although other compositions can be prepared by the method of thisinvention catalysts containing from about 7 to 22% by weight andpreferably from about 10 to 16% by weight of cobalt plus molybdenumoxides are employed. It is preferable that the molecular ratio of cobaltoxide to molybdic oxide (COO/M003) be between about 0.2 and 5.0 for bestresults. Within these limits the preferred catalyst will contain betweenabout 2 to 15% by weight of M00 and between about 12 to 0.5% by weightof C00.

Perhaps the process of this invention is best illustrated by thefollowing specific examples.

EXAMPLE I An alumina-silica gel containing an estimated 95% A1203 and 5%SiOz was prepared by the co-precipitation of an aqueous mixture ofsodium aluminate and sodium silicate with carbon dioxide. Theprecipitate was washed until substantially free of sodium ions, dried at90-110 C. and activated by heating for two hours at 600 C. A solution ofammonium molybdate was prepared by dissolving about 1700 parts by weightof ammonium paramolybdate, assaying about 81% by weight of M003, inabout 1940 parts by weight of 28% aqeuous ammonia and about 1550 partsby weight of distilled water. About 4400 parts by weight of theactivated gel were immersed in the ammoniacal solution of ammoniummolybdate, drained, dried and heated at 600 C. for about two hours. Anaqueous solution of cobalt nitrate was prepared by dissolving about 2150parts by weight of cobalt nitrate hexa-hydrate in about 2000 parts byweight of water. The carrier supporting the molybdic oxide was thenimmersed in the cobalt nitrate solution, drained, dried and activated byheating to 600 C. for two hours. The catalyst prepared by this methodcontained about 9.1% M00 and 4.4% C00; the atomic ratio of Co/Mo was0.93.

At the beginning of a run the catalyst was reduced at atmosphericpressure with hydrogen while controlling the rate to maintain thetemperature below 1050 F. after which time reduction was completed underpressure, such as at the reaction pressure to be employed. While continuing the hydrogen flow through the catalyst the preheated feed stockwas started through the catalyst bed and continued at the desired feedrate measured in terms of volumes of liquid feed stock per volume ofcatalyst per hour (also referred to herein as v./v.) and for the desirednumber of hours, after which time the hydrogen addition was continuedfor a short while in order to purge the catalyst of products.

The liquid product was cooled under pressure, withdrawn and washed withboth caustic and Water in order to remove any hydrogen sulfide andammonia. The washed and dried product was thereafter employed as a feedstock for contacting a freshly regenerated and reduced catalyst in asecond pass operation.

Employing the aforedescribed procedure a series of three double-passruns were made with an educted shale oil distillate having the followingcharacteristics:

Gravity, API at 60 F 27.2 Nitrogen, weight percent 1.72 Sulfur, weightpercent 0.74

All of the'runs were made with a hydrogen pressure of 1100 pounds persquare inch gage and at a catalyst bed temperature of about 770 F. Theadded hydrogen was varied from 3.7 to 4.0 thousand cubic feet per barrelof feed. In each case fresh non-recycled, once-through hydrogen wasemployed. The data obtained are presented in accompanying Table 1wherein column A represents data for a first-pass run and column Brepresents the data obtained by second-passing the product obtained incolumn A. Columns D and F similarly represent the secondpass data forfirst-pass runs reported in columns C and B, respectively.

Table 1 Column A B C D E F Pass 1st 2nd 1st 2nd 1st 2nd Conditions ofRun:

Catalyst Temp., F 700 700 770 700 700 700 Pressure, lb./sq. in. g l, 1001, 100 1, 100 l, 100 1, 100 1, 100 Added Hydrogen MCF/ bbl. of feed 4.3.7 4. 0 3.8 3. 8 3.8 Run Length, hrs 24 6 12 6 0 6 Vol. feed/vol.catalyst/hour. 0. 1.0 1.0 1. 0 2. 0 1.0 Product Analysis:

Nitrogen, Wt. (Percent). 0.35 0.07 0. 50 0. 11 0. 80 0. 22 Sulfur, Wt.(Percent) 0. 00 0.02 0.09 0.04 0.13 0.04 Carbon on Catalyst, Wt.(Percent) 5. 55 2. 51 5.08 3. l2 4. 91 3. Hydrogen Consumption, cu.

ft./bbl. of feed 950 nil 850 nil 650 (30) The data shown in Table 1 showthe high quality prodnot obtained by two-pass processing for the removalof nitrogen. Considering columns A, C and D, it is apparent that where acatalyst is employed with a feed rate of 0.5 volume of feed stock pervolume of catalyst a product containing 0.35% nitrogen can be obtainedfrom a feed stock containing 1.72% nitrogen. If, however, the samevolume of catalyst be divided into two equal portions and the same feedstock be denitrogenated in two stages, first over the first portion ofcatalyst and second over the second portion of catalyst withintervening. cooling of the product and washing to separate ammonia andhydrogen sulfide therefrom and with the use of uncontaminated hydrogenin the second stage, a product containing only 0.11% nitrogen canthereby be obtained.

it is also apparent that a product containing only 0.07% nitrogen byweight can be obtained from a feed stock containing 1.72% nitrogen byfirst processing the feed stock at a 0.5 v./v. and subsequentlyprocessing the first-pass product in a second stage operated at a 1.0v./v.

Excellent sulfur removal is shown for the first-pass product whilesecond-pass processing is necessary in order to reduce the nitrogen to acorrespondingly low figure.

EXAMPLE Tl When titania gel is substituted for the alumina-silica gel inthe catalyst preparation and processing described in Example 1',substantially the same favorable results are obtained.

EXAMPLE 111 A series of three cobalt molybdate catalysts supported onalumina were prepared by the co-precipitation method disclosed in theByrns patent cited hereinbefore. A fourth cobalt molybdate catalyst wasprepared by the co-impregnation method described in copendingapplication of Nahin et al. cited hereinbefore. The four catalysts werethen employed for desulfurizing a gas oil distillate from a Santa MariaVailey (California) crude oil. In each instance the catalyst was firstreduced and then employed for the desulturization for an operating cycleof six hours under the following conditions: a temperature of about 705F, a pressure of 150 pounds per sq. in., space velocity of 1.0 and with3000 cu. ft. of added fresh hydrogen per barrel of feed. in each casethe product of the reaction was cooled, washed with caustic to-removehydrogen sulfide, washed with distilled water and subsequently dried.The four products were then analyzed for sulfur. The data obtained fromthis series of four runs appear in accompanying Table 2.

6 EXAMPLE IV In this example a series of five impregnated catalysts wereprepared by three different impregnation procedures. Catalyst 1 and 2were co-irnpregnated catalysts prepared according to the methoddescribed by Nahin et al. in the copending application previously cited.

In the preparation of catalyst 1 an ammoniacal ammonium molybdatesolution was prepared by dissolving 104 parts by weight of ammoniumparamolybdate in a mixture of 190 parts by weight of 28% aqueous ammoniaand 123 parts by weight of distilled water. A cobalt-containing solutionwas prepared by dissolving 155 parts by Weight of cobaltous nitratehexahydrate in 65 parts by weight of distilled Water. Thecobaltcontaining solution was added slowly and dropwise into themolybdenum solution while rapidly stirring the m0- lybdenum solution. Acoprecipitated carrier containing about by weight of alumina and about5% by weight of silica was activated by heating for six hours at 600 C.About 420 parts by weight of the activated carrier were immersed in themixed solution for one hour, drained of the excess solution, driedovernight at 90 to C. and finally heated for two hours at 600 C.

Catalyst 2 was prepared in substantially the same manner as catalyst 1using a slightly difierent impregnation solution.

Catalysts 3, 4 and 5 were prepared by separately impregnating cobalt andmolybdenum in two impregnation stages with the cobalt being depositedfirst and the molybdenum second in the case of catalyst 3, and with themolybdenum, being deposited first and the cobalt second in the case ofcatalysts 4 and 5.

Catalyst 3 was prepared as follows: about 420 parts by weight of theactivated alumina-silica carrier were immersed in an aqueous cobaltousnitrate solution prepared by dissolving parts by weight of cobaltousnitrate hexahydrate in about 415 parts by weight of distilled water. Theimpregnated carrier was drained, dried and calcined for two hours at 600C. The carrier supporting the cobalt oxide was then immersed in anammoniacal ammonium molybdate solution prepared by dissolving 104 partsby weight of ammonium paramolybdate in a mixture of about 225 parts byweight of 28% aqueous ammonia and about 208 parts by weight of distilledwater. The impregnated mixture was drained of the excess solution, driedand activated by heating for two hours at 600 C.

Catalyst 4 was prepared as follows: about 420 parts by weight of theactivated alumina-silica carrier were immersed in an ammoniacal ammoniummolybdate solution prepared by dissolving about 104 parts by weight ofammonium paramolybdate in a mixture of about 225 parts by weight of 28%aqueous ammonium hydroxide and about 233 parts by weight of distilledwater. The impregnated carrier was drained of the excess solution, driedand calcined for two hours at 600 C. The carrier supporting the molybdicoxide was thereafter immersed in an aqueous solution of cobaltousnitrate pre pared by dissolving about 155 parts by weight of cobaltousnitrate hexahydrate in about 390 parts by weight of distilled water. Theimpregnated carrier was drained of the excess solution, dried andactivated by heating for two hours at 600 C.

Catalyst 5 was prepared in the same manner as catalyst 4 with theexception that the concentration of each of the two solutions waschanged to give a different catalyst composition.

The five catalysts were separately reduced and each was employed fordesulfurizing of a straight run gas oil distillate from a Santa MariaValley crude oil similar to that described in Example III. The gas oilfeed stock contained 2.33% by weight of sulfur and had a 33.2 APIgravity. The following operating conditions 7 were employed for thedesulfurization: a reaction temperature of about 750 F., a spacevelocity of 2.0 volumes of feed stock per volume of catalyst per hour, apressure of 150 pounds per sq. in. gage, an operating cycle of six hoursand 3000 cu. ft. of added hydrogen per barrel of feed. The products fromeach of the runs was processed in the manner described in Example I. Thedata obtained therefrom are shown in accompanying Table 3.

oil hydrocarbon stocks, which comprises passing said hydrocarbon stockin admixture with hydrogen through a catalyst contacting zone maintainedat a temperature between about 600 and 1200 F. and a pressure betweenabout atmospheric and 5000 p. s. i., said catalyst contacting zonecontaining a catalyst consisting essentially of a minor proportion ofcobalt oxide plus molybdenum oxide and a major proportion of anadsorbent carrier, said catalyst having been prepared by firstimpregnating Table 3 Catalyst number l 2 3 4 5 Method oiimpregna-tionCo+Mo Co+Mo Co first, Mo Mo first, Mo first, Co

. second. second.

Composition:

M003, weight percent. C00, weight percent... CoO+Mo0 Examination ofproduct:

Liquid recovery, volume percent. Sulfur in product, weight percent Acidsolubility, volume percent. Olcfins, volume percent 4 It is apparentthat highly active desulfurization catalysts are prepared byimpregnating the carrier in two separate stages wherein the molybdenumis deposited in the first impregnation stage and cobalt is deposited inthe second. The two-stage impregnated catalysts, wherein the M003 isdeposited first and the C00 second, are superior to the single stagecoimpregnated catalysts in that they give a higher yield liquid productwhich are also somewhat richer in aromatics as determined by subtractingthe olefin content from the acid soluble content. A comparison ofcatalyst 3 with 4 and shows that better desulfurization is obtained ifthe M003 is deposited first, rather than the C00 first, in the twostageprocess.

EXAMPLE V Catalysts 2, 3 and 5 prepared as described in Example HI werealso tested for the hydrofroming of a naphthenerich straight rundistillate having an A. P. I. gravity of 52.7 and containing about 12.7volume per cent aromatics. The following conditions were employed: Aprocess period of four hours, a space velocity of 1.0 volume of feedstock pervolume of catalyst per hour, a pressure of 100 pounds, anisothermal block temperature of 950 F. (temperature of large steel blocksurrounding the reactor tube) and 3000 cu. ft. of fresh added hydrogenper barrel of feed. The products of the runs were analyzed for aromaticcontent and the amount of synthetic aromatics was calculated by assumingthat the aromatics originally present in the feed stock passed throughthe reactor unchanged and were completely recovered in the products. Thehydroforming data for synthetic aromatics are shown in accompanyingTable 4.

Table4 Catalyst number 2 3 5 Method ofimprcgnatiorn... Co-l-Mo Co firstM0 M0 first, 00

second. second.

Composition:

000, Weight percent. M003. weight percent. 000 M003, weight percent.Synthetic aromatics. volume percent of feed.

This application is a continuation-in-part of my prior copendingapplication, Serial No. 88,046, filed April 16,

an adsorbent carrier which is essentially alumina with an aqueoussolution of a molybdenum compound, heating the once-impregnated carrierat an activation temperature above about 400 C. to thereby activate thealumina and decompose said molybdenum compound to the oxide formthereafter impregnating said carrier with an aqueous solution of acobalt compound and heating the twice-impregnated carrier at anactivation temperature above about 400 C. to thereby activate thealumina and decompose said cobalt compound to the oxide form.

2. A process for the desulfurization of mineral oil bydrocarbon stockswhich comprises passing said hydrocarbon stock in admixture withhydrogen through a catalyst contacting zone maintained at a temperaturebe tween about 600 and 1000 F. and a pressure between about atmosphericand 5000 p. s. i., said catalyst contacting zone containing a catalystconsisting essentially of a minor proportion of cobalt oxide plusmolybdenum oxide and a major proportion of an adsorbent carrier, saidcatalyst having been prepared by first impregnating an adsorbent carrierwhich is essentially alumina with an aqueous solution of a molybdenumcompound, heating the once-impregnated carrier at an activationtemperature above about 400 C. to thereby activate the alumina anddecompose said molybdenum compound to the oxide form, thereafterimpregnating said carrier with an aqueous solution of a cobalt compound,and heating the twice-impregnated carrier at an activation temperatureabove about 400 C. to thereby activate the alumina and decompose saidcobalt compound to the oxide form.

3. A process as defined in claim 2 wherein said catalyst comprisesbetween about 7% and 22% by weight of the r oxides of cobalt andmolybdenum and said carrier is aluminasilica containing between about 3%and 8% by Weight of SiOz.

4. A process for the hydroforming of mineral oil hydrocarbon stockswhich comprises passing said hydrocarbon stock in admixture withhydrogen through a catalyst contacting zone maintained at a temperaturebetween about 800 and 1200 F. and a pressure between about 50 and 1000p. s. i, said catalyst contacting zone containing a catalyst consistingessentially of a minor proportion of cobalt oxide plus molybdenum oxideand a major proportion of an adsorbent carrier, said catalyst havingbeen prepared by first impregnating an adsorbent carrier which isessentially alumina with an aqueous solution of a molybdenum compound,heating the onceimpregnated carrier at an activation temperature aboveabout 400 C. to thereby activate the alumina and decompose saidmolybdenum compound to the oxide form, thereafter impregnating saidcarrier with an aqueous solution of a cobalt compound, and heating thetwiceimpregnated carrier at an activation temperature above 9 about 400C. to thereby activate the alumina and decompose said cobalt compound tothe oxide form.

5. A process as defined in claim 4 wherein said catalyst comprisesbetween about 7% and 22% by weight of the oxides of cobalt andmolybdenum and said carrier is alumina-silica containing between about3% and 8% by weight of SiOz.

6. A process for denitrogenating a mineral oil hydrocarbon stock whichcomprises passing said hydrocarbon stock in admixture with hydrogenthrough a catalyst contacting zone maintained at a temperature betweenabout 700 and 1000 F. and a pressure between about 500 and 10,000 p. s.i, said catalyst contacting zone containing a catalyst consistingessentially of a minor proportion of cobalt oxide plus molybdenum oxideand a major proportion of an adsorbent carrier, said catalyst havingbeen prepared by first impregnating an adsorbent carrier which isessentially alumina with an aqueous solution of a molybdenum compound,heating the onceimpregnated carrier at an activation temperature aboveabout 400 C. to thereby activate the alumina and decompose saidmolybdenum compound to the oxide form, thereafter impregnating saidcarrier with an aqueous solution of a cobalt compound, and heating thetwiceimpregnated carrier at an activation temperature above about 400 C.to thereby activate the alumina and decompose said cobalt compound tothe oxide form.

7. A process as defined in claim 6 wherein said catalyst comprisesbetween about 7% and 22% by weight of the oxides of cobalt andmolybdenum and said carrier is alumina-silica containing between about3% and 8% by weight of SiO2.

8. A process for the catalytic upgrading of mineral oil hydrocarbonstocks, which comprises passing said hydrocarbon stock in admixture withadded hydrogen through a catalyst contacting zone maintained at atemperature between about 600 and 1200" F. and a pressure be tween aboutatmospheric and 5000 p. s. i., said catalyst contacting zone containinga catalyst consisting essentially of a minor proportion of cobalt oxideplus molybdenum oxide and a major proportion of an adsorbent aluminacarrier, said catalyst having been prepared by first impregnating anadsorbent carrier which is essentially alumina with an aqueous solutionof a salt of one metal selected from the class consisting of molybdenumand cobalt, heating the thus-impregnated carrier at an activationtemperature above about 400 C. to thereby activate the alumina anddecompose said impregnated metal salt to its oxide form, thereafterimpregnating the activated once-impregnated carrier with an aqueoussolution of a salt of the other of said metals, and subsequently heatingthe twice-impregnated carrier at an activation temperature above about400 C. to thereby activate the alumina and decompose saidlast-impregnated metal salt to its oxide form.

References Cited in the file of this patent UNITED STATES PATENTS2,253,308 Rosen Aug. 19, 1941 FOREIGN PATENTS 675,620 Great Britain July16, 1952

8. A PROCESS FOR THE CATALYSTIC UPGRADING OF MINERAL OIL HYDROCARBONSTOCKS, WHICH COMPRISES PASSING SAID HYDROCARBON STOCK IN ADMIXTURE WITHADDED HYDROGEN THROUGH A CATALYST CONTACTING ZONE MAINTAINED AT ATEMPERATURE BETWEEN ABOUT 600* AND 1200* F. AND A PRESSURE BETWEEN ABOUTATMOSPHERIC AND 5000 P. S. I., SAID CATALYST CONTACTING ZONE CONTAININGA CATALYST CONSISTING ESSENTIALLY OF A MINOR PROPORTION OF COBALT OXIDEPLUS MOLYBDENUM OXIDE AND A MAJOR PROPORTION OF AN ADSORBENT ALUMINACARRIER, SAID CATALYST HAVING BEEN PREPARED BY FIRST IMPREGNATING ANADSORBENT CARRIER WHICH IS ESSENTIALLY ALUMINA WITH AN AQUEOUS SOLUTIONOF A SALT OF ONE METAL SELECTED FROM THE CLASS CONSISTING OF MOLYBDENUMAND COBALT, HEATING THE THUS-IMPREGNATED CARRIER AT AN ACTIVATIONTEMPERATURE ABOVE ABOUT 400* C. TO THEREBY ACTIVATE THE ALUMINA ANDDECOMPOSE SAID IMPREGNATED METAL SALT TO ITS OXIDE FORM, THEREAFTERIMPREGNATING THE ACTIVATED ONCE-IMPREGNATED CARRIER WITH AN AQUEOUSSOLUTION OF A SALT OF THE OTHER OF SAID METALS, AND SUBSEQUENTLY HEATINGTHE TWICE-IMPREGNATED CARRIER AT AN ACTIVATION TEMPERATURE ABOVE ABOUT400* C. TO THEREBY ACTIVATE THE ALUMINA AND DECOMPOSE SAIDLAST-IMPREGNATED METAL SALT TO ITS OXIDE FORM.